1. Field of the Invention
This invention relates to a steering column, and more particularly, to a steering column for motor vehicle having a telescopic mechanism and a tilting mechanism.
2. Description of Related Art
The telescopic mechanism and the tilting mechanism of the steering column aim at adjusting the back-and-forth position and tilt angle of a steering wheel to the easiest-to-manipulate position according to the driver's body form and taste.
The telescopic mechanism and the tilting mechanism have a clamp/unclamp mechanism for adjusting the level and tilt angle of the steering wheel. When the adjustment is made, the clamp/unclamp mechanism is cancelled once, and is operated to clamp again after the adjustment.
The adjustment of forward-and-backward position and tilt angle of the steering wheel is performed by manipulating the steering wheel. Therefore, it is desirable to operate the clamp/unclamp mechanism without releasing the thumb from the steering wheel. There has been disclosed in British Patent No. 2281375 a steering column fitted with a single control lever which can be manipulated without removing the thumb from the steering wheel.
In the steering column disclosed in British Patent stated above, the movement of the control lever is transmitted to the back-and-forth position adjusting clamp apparatus through a cable movable in a flexible tube. The cable and the tube have a large-radius curve of a sufficiently little curvature so that the cable can freely move in the entire range of adjustment of the steering wheel. The cable, therefore, partly juts out of the outline of the steering column, not only looking awkward but becoming a cause of trouble. Moreover, the transmission mechanism including the cable and the tube not only has low reliability but can not smoothly operate because the cable is expandable.